Adjustable, modular instrument and method for spinal manipulation

Abstract

A spinal manipulation instrument, system, and method may use a driving rod to move instrument arms toward or away from one another to compress or distract between selected vertebrae to which the arms are connected. Two arms may be coupled to the driving rod. A threaded collar may axially engage one of the arms, to translate that arm along the driving rod with respect to the other arm. The other arm may be at a fixed axial location or driven by another, oppositely-oriented thread. The arms may be highly adjustable to accommodate a wide range of anatomical variation between patients. Attachment members may be modular to interchangeably couple the arms across multiple platforms.

What is claimed is: 
     
       1. A method, comprising:
 releasably coupling distal ends of first and second arms of an instrument to respective vertebrae, wherein proximate ends of the first and second arms are rotatably coupled to a driving rod about an axis defined by a threaded portion of the driving rod, the second arm having a threaded collar coupled to the threaded portion of the driving rod in axial engagement with the second arm; 
 releasably connecting, by a releasable threaded connection, the threaded collar and the threaded portion of the driving rod, the releasable threaded connection allowing for non-threaded axial re-positioning of the second arm along the driving rod when the threaded connection between the threaded collar and the threaded portion of the driving rod is released, the releasable threaded connection comprising a cam lever mechanism; and 
 after releasably connecting, rotating the driving rod with the threaded portion of the driving rod coupled with the threaded collar which is connected to the threaded portion, to translate the second arm along the driving rod with respect to the first arm, 
 prior to releasably connecting, further comprising: 
 sliding the second arm along the driving rod with the threaded collar released from the threaded portion of the driving rod to position the second arm adjacent the respective vertebra. 
 
     
     
       2. The method of  claim 1 , wherein releasably coupling the distal ends of first and second arms of an instrument to respective vertebrae comprises releasably coupling each arm to a bone fastener extending from the respective vertebra. 
     
     
       3. The method of  claim 2 , wherein releasably coupling each arm to the bone fastener comprises:
 selecting one of a plurality of modular attachment members having different attachment member configurations interchangeably connectable to the bone fastener; and 
 using the selected modular attachment member to couple a connector tip on the arm to the bone fastener. 
 
     
     
       4. The method of  claim 2 , further comprising:
 swiveling each arm about a swivel to a selected swivel angle and rotatably securing each arm to the respective bone fastener at the selected swivel angle. 
 
     
     
       5. The method of  claim 4 , further comprising locking each swivel at the selected swivel angle.